When comparing Gosu vs Wave, the Slant community recommends Wave for most people. In the question“What are the best 2D game engines?” Wave is ranked 35th while Gosu is ranked 48th. The most important reason people chose Wave is:
In addition to online [API documentation](http://waveengine.net/Engine/Documentation), the Wave Engine team provides [tutorials](http://www.indiedb.com/engines/wave-engine/tutorials) via IndieDB, plus [sample projects](https://github.com/WaveEngine/Samples) and "[QuickStarters](https://github.com/WaveEngine/QuickStarters)" via GitHub.
Ranked in these QuestionsQuestion Ranking
Gosu is not a game development framework, only a media library that happens to be suited to game development. (Kind of like SDL in the C world.) That means the interface is relatively small.
Pro Mature API, actively maintained and developed
Gosu has been under development since 2001. It is mature and has several toolkits built on top of it to provide additional functionality.
Pro Cross-platform, even mobile, using Ruby
Pro Supports coding in C#, F# and Visual Basic
Wave Engine explicitly supports all three core .Net Platform languages.
Pro Oculus Rift support
The Wave Engine team provides an official, open-source Oculus Rift extension via GitHub.
Con Deploying Ruby apps is a mess
Games built with the Ruby to .exe "compiler" do nothing more than extract your source code and Ruby.exe to %TEMP%, then run it. The code is not really compiled at all. The process for wrapping games as Mac apps is a bit nicer, but you'll need a paid Apple Developer subscription to code sign the app, or users will see a warning/error when running your game.
The only way to really compile Ruby is to use RubyMotion, which does not work on Windows and requires a paid subscription on top of the Apple Developer one.
(This Con is not specific to Gosu. Deploying Ruby code has never been fun.)
Con Mandatory splash screen
Games and applications made with Wave Engine must display a splash screen advertising it. No splash-free license option is available.
Con Not many tutorials available
Con Outdated UI
The UI looks like it is from Windows XP days. A refresh is much needed.